It is known in the art to prolong the life of spark plug electrodes by attaching various types of precious metal tip configurations to their firing ends. Some of the earliest examples of this technology are seen in U.S. Pat. No. 2,296,033 issued Sep. 15, 1942 to Heller, and in British Patent Specification No. 479,540 published in 1938 to Powell et al. The precious metal tips disclosed in these references are comprised of corrosion resistant materials, including platinum, platinum alloys such as platinum-rhodium, platinum-iridium and platinum-ruthenium, iridium, iridium alloys such as iridium-rhodium, as well as ruthenium, osmium and alloys thereof.
Furthermore, various methods, techniques and operating parameters for attaching precious metal tips have also been developed and utilized over the years. The particular materials or tip configurations used may affect which attachment technique or method is most affective. Several examples of these methods are disclosed in the following U.S. Pat. No. 5,558,575 issued to Chiu et al., U.S. Pat. No. 5,179,313 issued to Eves et al. and U.S. Pat. No. 6,304,022 issued to Matsutani.